This invention relates to a magnetic recording medium, more particularly to a magnetic recording medium remarkably improved in both chroma/audio characteristics and video characteristics, and also excellent in durability.
In recent years, a magnetic recording medium such as a video tape has been demanded to be improved in electromagnetic conversion characteristics remarkably. However, techniques which can satisfy this demand sufficiently have not been known so far.
In the prior art, it has been known a technique that by dividing magnetic layers laminated on a non-magnetic support to an upper layer and a lower layer, and generally imparting video characteristics to the upper layer and chroma/audio characteristics to the lower layer, high electro-magnetic conversion characteristics can be realized to the extent which cannot be achieved by a single layer tape. For example, there has been developed a magnetic recording medium in which transfer characteristics are improved or increase in light transmittance is suppressed by dividing magnetic layers laminated on a non-magnetic support to an upper layer and a lower layer, and incorporating a ferromagnetic alloy powder into the upper layer and a ferromagnetic powder into the lower layer.
However, sufficient chroma/audio characteristics cannot be obtained only by making the upper layer to have a film thickness of 1 .mu.m, and also when the film thickness of the upper layer is made 0.5 .mu.m or less, there is a problem that video characteristics tend to be lowered.
On the other hand, in a magnetic recording medium, not only improvement in electromagnetic conversion characteristics but also improvement in running durability have been demanded.
As a magnetic recording medium which can satisfy both demands, in Japanese Provisional Patent Publication No. 168124/1986, there is disclosed an attempt to improve electromagnetic conversion characteristics and running property at the same time by regulating a surface state of a magnetic layer of a magnetic recording medium by Ra which is an average roughness of a center line (defined in JIS B0601 (1976)) and R.sub.max which is a maximum height of unevenness of a surface. However, the techniques disclosed in the above patent publication cannot improve electromagnetic conversion characteristics and running property remarkably, and also it cannot reduce a rubbing noise effectively.